Absorbent articles, according to the present invention, are articles which can be used to absorb any type of fluid. These articles include absorbent hygienic articles (like for example sanitary napkins, pantyliners, tampons, inter labial articles, adult incontinence articles such as adult incontinence pads, pants and diapers, baby pants and diapers, breast pads and hemorrhoid pads). Other absorbent articles, according to the present invention, can be for example absorbent paper towels, wipes, toilet paper, or facial tissues as well as absorbent articles used in the medical field such as wound dressings and surgical articles and absorbent articles used in food technology and conservation (such as fluid pads for meat, fish and so on). Absorbent articles, according to the present invention, encompass also absorbent materials used industrially to absorb fluids (for example, to contain spillage of chemicals in fluid form).
Absorbent hygienic articles are commonly used to absorb, and in some cases, retain bodily fluids and other exudates excreted by the human or animal body, such as urine, menses, blood, fecal materials or mucus or chemicals or any type of fluid waste. Paper towels, wipes, facial tissues, toilet paper, and other absorbent articles may be used also to absorb kitchen and food residues and/or any kind of dirt or waste. In many cases, the absorbed materials can be malodorants or can generate malodors with time while the article is still being used, or after it has been disposed of or thrown in the trash.
Materials for controlling and reducing malodors in absorbent articles have been identified in the art. Odor absorbers (such as activated carbon, zeolites, silica and the like) have been widely used to trap volatile malodorant molecules in porous solids. Also, uncomplexed cyclodextrin molecules have been used to trap malodorant molecules by complexing them, and thus reducing their volatility therefore acting similarly to odor absorbers.
However, the action of odor absorbers is not always satisfactory, so that in the art they have been complemented or replaced by odor controlling organic compounds which play an active role in reducing the perception of malodors. Among these odor controlling organic compounds, fragrances (i.e. chemicals or blends of chemicals which stimulate the olfactory receptors providing a pleasant smell), odor masking compounds (i.e. compounds which stimulate the olfactory receptors so that unpleasant odors are perceived less or perceived as less disturbing), and reactive compounds (i.e. compounds which chemically react with the malodorant molecules altering their nature) are known and have been described e.g. in patent applications published under number EP1886698, EP2114331 EP2468308 EP3010555 EP3010554 EP3010553, all assigned to the Procter & Gamble Company.
It is also known from the art cited above, that these odor controlling organic compounds can be introduced into the absorbent articles in the form of complexes with cyclodextrin. This is beneficial in some cases, because fragrances and odor masking compounds are, by definition, volatile materials and therefore tend to evaporate from the absorbent articles during storage and use, thus losing efficacy. Most reactive compounds are also volatile, so the formation of cyclodextrin complexes prevents their evaporation as well. Moreover, all reactive compounds (volatile and less volatile) being “reactive”, they tend to have poor chemical stability. The formation of cyclodextrin complexes also protects the reactive molecules from unwanted reactions, greatly improving their chemical stability during storage and usage of the absorbent articles.
When odor controlling organic compounds are incorporated into absorbent articles in the form of cyclodextrin complexes, they are typically released from the cyclodextrin complexes when the article comes into contact with the fluids to be absorbed. This is typically the moment at which malodors can start developing and at which the release of odor controlling compounds is more necessary. This has also been described in the documents cited above.
Known cyclodextrin complexes are relatively effective in releasing the complexed odor controlling organic compounds, however, an aspect where an improvement can still be beneficial is improving the kinetics and the completeness of the release. As mentioned above, the need for controlling malodors typically occurs at the exact moment when a fluid is absorbed into the article (e.g. urine or menstrual fluids in hygienic articles, blood from food preparation absorbed by a paper towel and so on). Current cyclodextrin complexes, although very efficient, still require a certain amount of time to release the odor controlling compounds, and therefore in some cases, it is possible that malodors can be perceived (even if only for a short time) between the moment the fluid is absorbed and the moment when the odor controlling compounds are released.
The perception of menstrual or urine malodor when wearing an absorbent article is clearly unwanted, even if only for a short time, and it can cause embarrassment and loss of personal confidence. There is also a high demand for technologies which counteract malodors in the fastest possible way in the kitchen and among medical uses.
Based on the foregoing, what is needed is an absorbent article which utilizes an improved odor control composition, facilitated application of odor control composition, and/or improved placement of the odor control composition within the absorbent article.